Visitors to Paris's popular Museum of Natural History this weekend found a key exhibit under wraps after a man broke in and chainsawed a tusk from an elephant which once belonged to the Sun King, Louis XIV.

Police were called to the museum in the early hours of Saturday morning where they found a chainsaw still whirring after a man in his 20s escaped over a wall with a tusk over his shoulder. A police official said a neighbour of the museum on Paris's Left Bank alerted authorities after hearing a strange sawing sound at around 3am. The museum alarm system was activated and startled the intruder into fleeing just minutes after beginning his chainsaw attack. He was treated in hospital for a fractured ankle from a fall while escaping and was being questioned by investigators.

The African elephant, whose left tusk was sawn off, was a gift from a Portuguese king to Louis XIV in 1668. It lived for 13 years in the royal menagerie in the grounds of the opulent palace of Versailles where it became the star attraction. When it died, its skeleton was transferred to the natural history collection in Paris, one of the biggest in the world alongside London's Natural History Museum.

The museum, which has 1.9 million visitors a year, opened as normal over the weekend but with the damaged elephant skeleton draped in plastic wrapping behind a notice that it was being restored. Jacques Cuisin, head of restoration at the museum, said the 3kg tusk did not have a great monetary worth, but it had major historical and scientific value and would be repaired. The tusk was not an original but had been added to the skeleton in the 19th century.

There has been a spate of thefts of rhino horns and elephant tusks from European museums, zoos and auction houses in recent years, amid a rising illegal trade in poached or stolen ivory. On the black market an elephant tusk can fetch hundreds of pounds per kilogramme, with rhino horns fetching considerably more. The international trade in elephant ivory has been outlawed since 1990 after a sharp decline in elephant populations.

In 2011, several major European museums removed rhino horns from display and replaced them with replicas following warnings from police after a wave of museum thefts believed to be linked to criminal gangs. Among the horns stolen in night-raids was that of Rosie the rhino, a key exhibit at Ipswich Museum and the mounted head of a black rhino stolen from an Essex auction house the day before it was due to be sold.